FPGA embedded system for ultrasonic non-destructive testing

Abstract

Long Range Ultrasonic Testing (LRUT) is an emerging ultrasound Non-destructive Testing (NDT) method. The LRUT is a variant of the conventional NDT approach. By using ultrasound guided waves (UGWs) , it is efficient in quick long range defect scanning, which is impossible with other traditional NDT techniques. Increasing numbers of requirements for quick long range testing have led to urgent need for the improvement of testing methods and the development of new testing equipment to help researchers in laboratory and help technicians in field inspection. The market for multi-channel ultrasonic instruments is characterized by small volumes of sales and a high ratio of development costs to sale price. The consequence is that the investment required to develop an instrument is significant and upgrades and other changes to instrument specification or configuration are difficult for many manufacturers to justify. These factors are particularly relevant for long range guided wave technology, where the technology is still relatively new in the market place and the instrumentation has different characteristics from other type of ultrasonic systems. In order to support the design and manufacture of the Teletest®MK4 system, Plant Integrity Ltd has supported this study into the use of a field-programmable gates array (FPGA) based control circuits for the electronics, which allows the component count to be decreased and also permits the system to be modified via flexible reconfiguration of the FPGA. This has benefits of reduction of size, weight and power consumption of the electronics and provides a means of upgrading the product without expensive re-design of the hardware. FPGA device has been the enabling technology and main thrust behind the evolution of many technologies, unleashing new opportunities for improving the performance of the LRUT equipment and providing more functions for industrial and academic applications. A novel system has been developed to provide multichannel waveform generation, data capture and signal processing for advanced lab-based research and faster- field testing. This system includes an FPGA to process multichannel data in parallel and to provide the flexibility of reconfiguration for various testing applications proposed by new research. The design was tested in pre-prototype hardware. Subsequent construction of the commercial prototype unit enabled successful operation of the design to be demonstrated. Implementation of the FPGA design reduced component count, PCB dimensions and power consumption. Though the SpartanTM 3A DSP FPGA and Xilinx ISE software have been used in this project, the concepts of the design can be applied to other FPGA devices from other FPGA vendors using other design softwares.